1. Field of the Invention
The present invention relates to an endoscope apparatus, in particular, an endoscope apparatus for observing the alimentary canal at the depths such as intestinum tenue, large intestine, etc., in which balloons are attached to the distal end of the endoscope insertion portion.
2. Description of the Related Art
Where the insertion portion of an endoscope is inserted into the alimentary canal at the depths such as intestinum tenue, etc., it is difficult to transmit a force to the distal end of the insertion portion due to complicated bending of intestinal tracts only by pushing and inserting the insertion portion thereinto, wherein it is difficult to insert the insertion portion into the depths. For example, if excess bending and deflection are brought about at the insertion portion, it becomes impossible to insert the insertion portion further into the depths. Therefore, such an operation method has been proposed, in which the insertion portion of an endoscope is inserted into an insertion assisting member and is then inserted into a body cavity, and the insertion portion is inserted into the depths while preventing excess bending and deflection of the insertion portion by guiding the insertion portion by means of the insertion assisting member.
For example, JP-A-2002-301019 discloses an endoscope apparatus in which a first balloon is mounted at the distal end of the endoscope insertion portion, and simultaneously, a second balloon is mounted at the distal end of the insertion assisting member (a so called over-tube or sliding tube).
By expanding the first balloon and bringing the same into contact with the inner wall of the intestine, it is possible to provisionally fix the distal end of the insertion portion in an intestinal tract. Similarly, by expanding the second balloon, it becomes possible to provisionally fix the distal end of the insertion assisting member in the intestinal tract. Therefore, by inserting the insertion portion and the insertion assisting member by turns and hauling in the same while causing the first balloon and the second balloon to expand and contract, the insertion portion can be inserted into the depths of a complicated and bent intestinal tract such as an intestinum tenue.
Also, the first balloon of JP-A-2002-301019 is connected to an air tube via the inlet/outlet port of the air hole formed at the distal end of the insertion portion, wherein the first balloon is expanded with air supplied through the air tube and is caused to contract with air sucked in via the air tube. The inlet/outlet port of the air hole and the air tube are cleansed by the balloon being removed after use.
In this connection, in the endoscope apparatus according to JP-A-2002-301019, the inlet/outlet port of the airhole for supplying air into the first balloon is formed in the direction orthogonal to the axis of the insertion portion of the endoscope. That is, since the air tube disposed along the axis of the insertion portion is coupled to the inlet/outlet port of the air hole at a right angle, it was difficult for a brush to be inserted into the air tube through the inlet/outlet port of the air hole when cleansing the inlet/outlet port of the air hole and the air tube. Therefore, in the endoscope apparatus according to JP-A-2002-301019, brush cleansing could not be carried out, wherein there was a problem in that the cleansing was dependent only on a drug solution.